For heat treatment purposes of different types there have been developed different types of ovens for drying, hardening and food processing. An oven type, which has been developed in a number of different, well operating embodiments, during the last decade, is the IR-oven, which with a plurality of infrared radiators heat the goods to be treated in the oven. By particular steps it has hereby been possible to adapt the heating effect and the heat distribution in a desired manner, whereby ovens entirely or partly equipped with IR-elements, have proven themselves very well suited for many different purposes. For the purpose of combining the IR radiation with convection heating it has in certain types of ovens beside IR-elements in the oven walls also been provided an electric heating battery, which gives convection heating. This gives the heat treatment an improved flexibility, which is desirable in many connections.